1. Field of the Invention
Aspects of the present invention relate to a fuel cell, and more particularly, to a fuel cell having an actuator control unit and a method of operating the same.
2. Description of the Related Art
A fuel cell system is an apparatus that generates energy using fuel such as methanol. The fuel cell system generally includes a fuel cell and a cartridge. The fuel cell is an electricity generation device that generates electrical energy by reacting hydrogen from a fuel and oxygen from the air. The cartridge is a fuel tank that supplies the fuel to the fuel cell.
FIG. 1 illustrates the structure of a conventional fuel cell system SS1. Referring to FIG. 1, a fuel cell 10 includes a fuel cell stack 10A, a buffer 10B, and an actuator 10C. The fuel cell stack 10A generates electricity and includes a plurality of unit cells. The actuator 10C delivers fuel from the cartridge 12 to the buffer 10B. When the cartridge 12, which supplies fuel to the actuator 10C, is regarded as primary fuel storage of the fuel cell system SS1, the buffer 10B can be secondary fuel storage. The buffer 10B temporarily stores the fuel supplied by the actuator 10C and supplies an amount of the fuel to meet the needs of the fuel cell stack 10A. Since the amount of fuel instantaneously used by a load on the fuel cell system SS1 is variable, the amount of fuel consumed by the fuel cell stack 10A varies. The buffer 10B supplies the fuel to the fuel cell stack 10A corresponding to the amount of fuel consumption of the fuel cell stack 10A, which varies at each moment.
The fuel amount consumed by the fuel cell stack 10A can be greater than the amount of fuel supplied from the actuator 10C to the buffer 10B. In other words, the amount of fuel output from the buffer 10B can be greater than the amount of fuel input to the buffer 10B. As the buffer 10B is used as the secondary fuel storage, the buffer 10B is able to compensate when the amount of fuel output from the buffer 10B is greater than the amount of fuel input to the buffer 10B for a period of time.
However, when the amount of fuel output from the buffer 10B is continuously greater than the amount of fuel input to the buffer 10B, even when the buffer 10B is regarded as the secondary fuel storage, the buffer 10B may not be able to provide a necessary amount of fuel to the fuel cell stack 10A. In such a case, the buffer 10B may run out of fuel to supply to the fuel cell stack 10A and portions of the buffer 10B may become dry.
In contrast, the amount of fuel consumed by the fuel cell stack 10A and supplied from the buffer 10B can be less than the amount of fuel input to the buffer 10B. If such a case is not continuous or not continuous for an extended period of time, the buffer 10B can compensate if the buffer 10B is not full so that the buffer 10B has fuel storage capacity to accept the greater input of fuel than output. However, when the buffer 10B is completely filled with fuel, the amount of fuel input from the actuator 10C to the buffer 10B is supplied to the fuel cell stack 10A, resulting in the fuel being excessively supplied to the fuel cell stack 10A.
When the fuel cell system SS1 is in an off state, the fuel remaining in the fuel cell stack 10A continuously reacts. As a result, the performance of the fuel cell stack 10a may be degraded. Furthermore, when the fuel cell system is turned off in a state in which the fuel cell stack 10A is excessively filled with fuel, the degradation of performance of the fuel cell stack 10A can be more serious. This leads to a decreased efficiency and a lower fuel utilization of the fuel cell system SS1.